Halfway Number
What is the halfway number between 10 and 20?
15
602-371
231
71+12
83
86-23
63
Round to the nearest ten
321
320
What is the halfway number between 20 and 30?
25
705-212
493
723+134
857
745-23
722
Round to the nearest hundred
3,456
3,500
What is the halfway number between 100 and 200?
150
507-298
209
37+26
63
Use this strategy when numbers are not great
74-6
Think:74 subtract 4 (one part of the 6) is 70 and 70 subtract 2 (the other part of the 6) is 68.
Round to the nearest hundred
5,653
5,700
What is the halfway number between 1000 and 2000?
1500
6,204-2,352
3,852
Use compensation
52+39
Think: 52 plus 40 is 92, but I added one too many to take me to the next 10, so to compensate: I subtract one from my answer, 92-to get 91
91
Use Compensation
56-18
but I subtracted 2 too many; so, I add 2 to the answer to get 38
Round to the nearest thousand
3,999
4,000
What is the halfway number between 1,000,000 and 1,000,010?
1,000,005
8000-3,644
4,356
Use Compensation
345+198
Think: 245+200 is 545, but I added 2 too many, so I subtract 2 from 545 to get 543
543
Use compensation
145-99
Think: 145-100 is 45, but I subtracted 1 too many; so, I add 1 to 45 to get 46
Round to the nearest thousand
2,387
2000